Bee deaths lead to more questions than answers

Moratorium proposed on use of pesticides

Long after life returns to normal and the netting comes off the trees in the Target parking lot in Wilsonville, researchers will still be conducting tests and research to learn more about the massive bee die-off that started June 15 after 55 trees were treated with a pesticide.

For Oregon State University Extension Entomologist Sujaya Rao, an expert on bumblebees and native bees, the work has only begun.

Rao has been back to the parking lot several times since the dying bees were first discovered. The good news is that though dead bees are collecting inside of the nets, no new significant deaths are being found on the ground.

On June 27, the Oregon Department of Agriculture put temporary restrictions on the use of 18 pesticides that contain the active ingredient dinotefuran while it investigates massive bumblebee die-offs in Wilsonville and Hillsboro.

In Wilsonville, more than 50,000 bumblebees, representing an estimated 300 wild bumblebee colonies, died after coming in contact with flowering linden trees treated with a pesticide used to control aphids. Honeybees were found dying in Hillsboro just days later near trees treated with the same product. Scientists are calling this the largest event of its kind ever documented.

According to Xerces Society, an environmental organization that focuses on invertebrates, the pesticide used, dinotefuran (sold commercially as Safari), belongs to a relatively new and controversial group of chemicals called neonicotinoids.

Because neonicotinoids are long-lasting in plant tissues and can be found in flower nectar and pollen, and because they have been implicated in the global decline of honeybees, there have been growing concerns about their safety for pollinators, the Xerces Society stated in a July 12 release.

When Rao heard of the Wilsonville die-off, her initial reaction was, Oh, my god. Thats an awful lot of bees.

Her next thought, however, was to wonder why it was bumblebees and not honeybees.

From a scientific standpoint, researchers have many questions to answer. Why that particular species of bumblebees, why those trees, why that pesticide and what roles they all played in the die-off.

There are other variables as well. In Europe, there have been cases of untreated linden trees also killing bees. Also, if a tree is stressed and unhealthy, it produces more flowers, which in turn attract more bees, according to Rao. That stress also produces a residue in the nectar, which could harm bees.

Because the nectar levels were already low during the Wilsonville incident, Rao said researchers could not collect enough to use for testing and study, which further complicates their task.

Bee deaths are of growing concern

Although the high concentration of bumblebees near the poisonous trees in Wilsonville alluded to good news that there are larger populations of wild bumblebees than previously thought, the deaths are a growing concern.

Hives of honeybees are common around the state, as they are easy to manipulate and move. Bumblebees, however, are superior natural pollinators, but they cannot be controlled as easily, according to Rao. In Oregon, one cannot buy bumblebee colonies.

Bumblebees play a vital role in Oregon agriculture, as the state grows between 200 and 300 different crops, many of them from seed, which especially need pollination.

It will remain unknown until next year if the massive die-off will make a difference for future crops.

Overall, the more bees that died, fewer are left to produce new queens, Rao said. The number of queens left this year affects colony numbers next year.

For the Oregon Association of Nurseries, which is based out of Wilsonville, pest control can determine the success or failure of nursery products.

We are very concerned when something like this happens. It serves as a reminder that one must always follow the instructions and read the warning when using any chemical, no matter if the chemical is an herbicide, a pesticide or a fertilizer, said Curt Kipp, senior publications manager for Oregon Association of Nurseries. That goes for growers as well as the gardener at home.

Kipp said since nurseries typically propagate by grafting cuttings or buds onto rootstock, there is not as much reliance on bees from them as there is for food producers. Growers can use a variety of means to control pests, such as using pesticides, beneficial insects and bug safe chemicals.

These pest control methods are up to each individual grower and will vary based on the grower and the situation. When nursery workers apply any type of insecticide, they must first be trained and certified to do so. This is for the safety of the worker as well as the health of the plants and the well-being of the environment, Kipp said.

Rao said the evolution of pesticides keeps changing, referencing DDT (dichlorodiphenyltrichloroethane) from the mid-1900s. DDT was banned in 1972 after it was found it may cause cancer and birth defects and was a threat to birds and their shells, nearly causing the extinction of the bald eagle.

Now we need to start looking to reduce risks to pollinators, Rao said, adding that it is difficult because bees have many similarities to other insect pests. We could all go organic, but would that feed the worlds population (in) 2050? Wheres the solution?

Solutions in the works

For some, the answer is banning certain pesticides to protect pollinators.

On Friday, Xerces Society Executive Director Scott Hoffman joined Congressman Earl Blumenauer (D-Portland), who introduced the Save American Pollinators Act. The national legislation suspends the registration of any neonicotinoid for use in seed treatment, soil application or foliar treatment (application to the leaves of trees) on bee-attractive plants until the Environmental Protection Agency reviews the chemicals and makes a determination about proper application and safe use.

In April, the European Union created continent-wide restrictions on the use of bee-harming pesticides. A majority of member nations voted to place a two-year ban on the use of three neonicotinoids suspected of doing harm to bees, according to the Oakland-based Pesticide Action Network.

That group praised Blumenauers effort, saying the U.S. Environmental Protection Agency and U.S. Department of Agriculture had failed to address concerns about neonicotinoid pesticides.

As for the city of Wilsonville, according to Director of Public Works Delora Kerber, the city does not use any of the pesticides that were recently banned by ODA and the ban does not impact the way it conducts pest and weed control.

For the home gardener, Xerces Society recommends against using neonicotinoids as well as creating patches of pesticide-free, pollinator friendly flowers to attract bees.

Kipp would add that local nurseries are ready to help gardeners select annuals, perennials, shrubs and trees to encourage the bee population.

By encouraging bees, gardeners can improve pollination for fruit, berries and even herbs they grow themselves, as well as their ornamental plants, he said.